Class III anti-arrhythmic agents may be categorized as having the ability to markedly prolong dog Purkinje fiber action potential duration without producing significant changes in maximal upstroke velocity. Unlike Class I anti-arrhythmic agents, a pure Class III agent displays no effects on cardiac sodium channels. The electrophysiologic properties of a compound defining a Class III activity profile are observed in vivo as negligible effects on atrial, ventricular and H-V conduction lines while producing a marked increase (greater than 20 percent) in both the atrial and ventricular refractory period. In contrast, Class I agents will demonstrate a marked slowing of ventricular conduction velocity, generally without significant changes in the refractory period. Recent reviews of these agents are by Bexton et al., Pharmac. Ther. 17, 315-55 (1982); Vaughan-Williams, J. Clin. Pharmacol. 24, 129-47 (1984) and Thomis et al., Ann. Rep. Med. Chem. 18, 99-108 (1983).
German Offenlegungsschrift 1912848 discloses in Example 5 the intermediate N.sup.1 -(2-isopropylaminoethyl)-N.sup.4 -acetyl-sulfanilamide which is used to produce 1-sulfanilyl-2-imino-3-isopropyl-imidazolidin said to be useful as a hypoglycemic agent.
Silberg et al., ACAD Rep. Populace Romire, Fillala Clug, Studee Cercetari Med., 10 244-52 (1959) discloses p-acetylamino-N-(2-diethylaminoethyl)benzenesulfonamide among other compounds compared in their anti-arrhythmic properties with procainamide.
The Abstracts of Papers to be presented at the 192nd ACS National Meeting, Sept. 7-12, 1986 at Anaheim, Calif. reports Abstract 9 by R. A. Wohl et al. which discloses N-[2-(diethylamino)ethyl]-4-[(methylsulfonyl)amino]benzamide hydrochloride projected as a potential Class III anti-arrhythmic agent.